This section is from the book "Materia Medica: Pharmacology: Therapeutics Prescription Writing For Students and Practitioners", by Walter A. Bastedo. Also available from Amazon: Materia Medica: Pharmacology: Therapeutics: Prescription Writing for Students and Practitioners.
These are agents which are soothing and softening to epithelial tissues. Their action is essentially physical or mechanical, and is purely local. Those for application to the skin are called emollients; those applied to mucous membranes are demulcents.
The emollients include the unctuous materials, such as lard (adeps), wax (cera), spermaceti (cetaceum), petrolatum, cold cream (unguentum aquae rosae), ointment of zinc oxide, etc.; also cocoa-butter, olive oil and other bland oils, talcum powder, glycerin, rose-water, and various soothing lotions. The object of their use is to prevent drying of the epithelium or to soften and protect dried or irritated tissues. They are employed, therefore, for chapped skin, chafing, dermatitis, burns, etc. Poultices and hot fomentations are sometimes considered emollient, but they are best classed with the hot-water bag under the heading Coun-terirritants.
The demulcents are the mucilaginous substances, such as acacia, tragacanth, flaxseed (linum), slippery elm (ulmus fulva), althaea, sassafras pith (sassafras medulla) and Irish moss (chon-drus crispus); also licorice (glycyrrhiza), sweet almond (amygdala dulcis), starch (amylum), milk, white of egg, and the bland fixed oils (almond, olive, linseed, cottonseed, etc.). In the form of lozenges, flaxseed, slippery elm and licorice are employed in sore throat. In liquid form a demulcent may be taken by mouth for esophageal or stomach irritation, as following the ingestion of irritant poisons, or injected by rectum for proctitis or colitis or other irritative conditions. (For Starch Water, see Starch, in Part I.)